The present invention relates to a hydraulic pressure system mounted to a rotor hub assembly, and more particularly to a hydraulic pressure system mounted between a standpipe and a rotor shaft of a rotary wing aircraft.
Multi-element airfoils are in common use on fixed wing aircraft. Such applications, however, are either in a fixed configuration or activate at relatively slow rates. In conventional applications, the aerodynamic flow environment is steady or quasi-steady conditions.
Multi-element airfoil application to rotary-wing aircraft has concentrated upon individual blade control of each rotor blade wherein each rotor blade is pitched individually a multiple of times during each revolution of the rotor blade. Other multi-element applications utilize various slats, flaps and/or other aerodynamic surfaces that are selectively deployed from each rotor blade a multiple of times during each rotor blade revolution. These actuation systems provide numerous design challenges as significant power must be available to each rotor blade. The actuation system must also generate high flow rates to operate the actuation system a multiple of times during each revolution to provide individual blade control.
Conventional actuation systems utilize a remotely located hydraulic pressure system that feeds fluid pressure to each rotor blade through a hydraulic slip ring and conduit system. Disadvantageously, seals within the hydraulic slip ring may have an unacceptable service life. The numerous feed and return lines which are required to power the individual blade control of each rotor blade may also be relatively complicated and require significant maintenance. Moreover, hydraulic systems with pressures sufficient to provide the required actuation force and responsiveness require relatively large and heavy power systems.
Accordingly, it is desirable to provide a hydraulic pressure system for a rotor hub assembly which is powerful and generates high flow rates yet, is light in weight, compact and minimizes the communication of pressurized fluid through rotational interfaces.